The present invention relates to the methods of obtaining the adjustable capacitor for low-voltage and high-voltage.
Known mechanical method of obtaining an adjustable capacitor uses the step of changing the distance between capacitor plates or the step of changing the active area of capacitor plates.
This method has the following shortcomings:
It is difficult to make this capacitor hermetic; PA1 The capacitor can change its electrical characteristics because it is not hermetic and in consequence of friction between moving parts; PA1 It is not expedient to use a mechanical method for capacitors with a big capacity, for high voltage capacitors, for Power-Factor-Correction Capacitors, for Vacuum Capacitors and for Gas Capacitors; PA1 It is not possible to use a mechanical method for changing capacities of Electrolytic Capacitors which plates are realized as spirals; PA1 The peak of energy density is not high; PA1 The maximum rate of changing a capacity of a capacitor cannot be high.
U.S. Pat. No. 3,569,795, Cl.317/231 of Gikow is an example of well known voltage variable capacitors of alternating current in which a capacity of a capacitor is changed as a result of the effect of changing a dielectric constant of a ferroelectric material by direct current control voltage. The capacitors of this type can not decrease a capacity of the capacitor to zero by said control voltage and have relatively narrow range of changing a capacity and the used principle of changing a capacity cannot transform other types of capacitors into variable capacitors.
Gikow, in U.S. Pat. No. 3,562,637, Cl.323/74, uses direct current control voltage, applied to each capacitor from a plurality of capacitors (at least four capacitors), for obtaining the adjustable capacitor of alternating current. The control voltage creates on each of the pairs of said capacitors, connected together in series, voltages which have opposite directions and counteract each other. In this technical solution all energy of charging of said serially connected capacitors can not be discharged and the energy, which can not be discharged, is approximately proportional to (CU.sub.C).sup.2 where U.sub.C is the control voltage, C is the capacitance of one of said capacitors. The mentioned short comings decrease the range of changing the capacity and do not permit obtaining an adjustable Power-Factor-Correction Capacitor, an adjustable capacitor for an electric circuit which actuates a resonance, an adjustable capacitor whose capacity can be decreased to zero. Said plurality of capacitors can not provide a rapid extraction of the stored energy into a load because voltages on each of the pairs of said capacitors have opposite directions and the electric charges on each of two connected together plates of said capacitors are the same: positive or negative. For obtaining th e adjustable capacitors according to both Gikow U.S. Pat. Nos. 3,562,637 and 3,569,795, it is necessary to use a source of control voltage of direct current with resistors and to recuperate relatively high energy losses on said resistors.
A conception which permits transforming all types of invariable capacitors into variable capacitors does not exist in the art and an adjustable Electrolytic Capacitor and an adjustable Power-Factor-Correction Capacitor, with stepless control of capacity, do not exist on the market.